Production of latex compositions



H 'Patent'ed Feb. 17, 1931 Let -Q oULAs mam Twigs Ami EDWARD anrnun Mun-Pity, or Bmmmsm, ENGLAND, ASSIGNORS 'ro DUNLOP RUBBER COMPANY LIMITED, 01" BIRMINGHAM, ENGLAND, nconronn riorv or GREAT BRITAIN, v y

1 ssosvcmiqgermwsx co irrosrrrons No nrawni f a ii itaa 'fiiea mne a e'aa'ser No. 368,399, and in Great SBrltainfJ'uIy 25,1,192'a' 1 5 whic-hhave low water contents, for example "iii substances which have as their principal;-

function to serve, 1n place of water, as a This invention is concerned with {the pro.- duction from aqueous dispersionsloffor containing rubber or similarrrmaterials of'compositionsof pasty orplasticsolid consistency 3 per cent or even'lower than this, but are still substantially reversible in water andareparticularly suitable for extruding and mould-' ing and for the preparation of rubber sheet."

It is knownto incorporate suitable proportions of' protective colloids into rubber latex and to subjectthe latex to evaporation and soaps have been used for this purpose.

We have found that during evaporation of 5: latex a stage of dehydration is reached when the protective colloids, artificially incorporated, as well as the natural colloids occurring in the latex, cease to function, with the 7 result that further evaporation of water causes the latex to coagulate. I

and/or compounded condition, one or more meduim wherein'the protective colloids both naturally occurring and artificially lncorporated, will continue to function when the "no water in the dispersions is substantially removed (for example to about three per cent or lower) by further evaporation and we continue the evaporation until products of pasty or plastic solid consistency are obtained 5 which are still substantially reversible in water. kEvaporation is conveniently carried out at or below 40 C. with gentle stirring, thus ensuring a continuous exposure of fresh surdesired the rate of evaporation can be increased by a reduction of the atmospher c pressure.

It has been found that the addition for the. particular purpose specified of the substances hereinafter mentioned serves'also' to prevent drying of the outer surfaces and aids the transference of water from the lnterior of the rubber dispersion to the atmosphere durlng the concentration. Examples of substances According to this invention we add to an aqueous dispersion of rubber such as rubber latex, which may be already 1n a concentrated a l' 'd 1 faces during the evaporatlon process. If 1 flmtmg qul's which will give the aforesaid desired result are polyhy droxy compoun'ds'such as poly hydricalcohols or their derivatives suchas glycerohglycol, diethylene glycol or allryl ethers of these such? as glycol monoethyl ether, f i f i f The colloidswhich have beenj'found suitable for gincorporation into the latex are soapssuch as potassium ole'ate orricinole'ate (readily soluble soap's of other alkali metals is are also applicable as-also are the saltsof fatty acids with organic'bases such as-piper- ,7 idine oleate. Compounds of the first class,

-e.-*g.,piperidinef joleate'haveflan additional advantage in that they aresu'fficiently stable to persist and remain effectivefduring the evaporation 5 process but may iundergo "decomposition duringthe final ifoperationf 6f vulcanization thereby QaiIding vulcanization and also eifecting the' disappea waterbysubjecting them'tothe influence of ing, extruding, calendering or kneading-1 If desiredthe stability of the'p'astes or plastic solids can be further reducedbytheyincor- -poration of small quantities of destabilizing agents such formaldehyde] orcal'ciuin sulphate in order a to, hasten the desired c0la lescenceionthe application of the forces profldu ced' by extrusion," moulding; or calender-Y -1ng.- 1 The products may also. be rendered irreversible by the applicationio'f heat, or by Anexample of be concentrated to about. 3 'per cent-j water content under the conditions herinbefore-indicated to yielda reversible paste which befor instance on being extruded,

comes solid, I is as follows:

ace-crane treatment i with coagulating[and/or I dehy- I a composition which can (ill mechanical treatment such as occurs in mouldj 7 those skilled in the art without departlng 'be removed from the articles formed from the; pastes by, for example, extrusion or moulding, by washing in water. If the come pounding ingredients include an ultra-accelerator and sulphur, this washing may conveniently be madeto take place concurrently with vulcanization by heating the articles in A c sa1d dlsperslon being'substantlally removed.

boiling waterl Various modifications may be made 'by from the invention as defined inthe appended claims. V What weclaim is: c.

1. A process for the production of substan- I tially reversible compositions of pasty con--v sistency from aqueous dispersions containing rubber or similar ,ma terialsand a protective.

colloid which consists inevaporatingf the aforesaid dlspersions 1n thejpresence of one or more substances which have as tl1eirprin-.:

cipal function toserve, in place of water, as

i a mediumwherein-the protective colloids "10. The process as claimed in claim 1 wherein soluble soaps are added as protective colloidsto the aqueous dispersions.

-11. A reversible aqueous dispersion containing rubber materials and a protective colloid of-pasty, constituency and containing a medium wherein the protective colloids continue tofunction, the Water content of 12. The product of claim- 11in which the Water content of the ,dispersion is about three percent.

13. The roduct of claim 11 in which the medium in which said protective colloid functions is a'polyhydric alcohol.

14. I The composition of claim 11 in which .afsmall quantity of a destabilizing agent is contained,

In wltness signed our names.-

noUGLAsFRA NKiTWIss. i EDWARD ARTHUR MURPHY.

whereof, f we I have hereunto both naturally occurring and artificiall V,

corpo-rated, will continue to function when p 1 the waterinthed spersions is substantially removed. r

2. The process as claimed in;;.;claim 1, i

said dispersions to serve in the aforesaid -Wherein the substancesadded to the aforepolyhydric alcohols o-r their derivatives such i I as glycerol, glycohdiethylerie glycol or alkyl ethers of these such as.

glycol mo-noethyl ether.- I

3. The process' asrclaimed in claim 1 wherein theaqueous dispersionof or containingrubber or similar materials is rubber latex.

wherein the stability of the reversible com- 7 water:

positions of pasty or plasticconsistency is reduced by the incorporation; into the p 4. The process as claimed in claim 1, wherein the aqueous, dlsperslo-ns "3.113 111 a concentratedcondition.

aqueous dispersions aforesaid o tsmall quantities of destabilizing agents such as format dehyde or calcium sulphate.

subsequently l. The. process as claimed in claim '1,- wherein the protective ingredients added are removed by washing with I 8. The process :as claimed inclaim '1,

wherein the evaporation is proceeded with until the reversible products of pasty or pla'ctic solid consistency obtained have a as 3% substantially as water content as low described.

9. The process as claimed in claim 1 wherem the aqueous dispersions are in com- I poundedcondltlon. 

